Marking machines of the type as stated in the opening paragraph are known, in which, when marking a sheet-shaped object, the embossing wheels mounted on the embossing wheel shaft at a time are pressed down towards the object by means of the pressure of the holding cylinder, the total embossing pressure is relatively high, since the total embossing pressure is equal to the sum of the embossing pressures of each embossing wheel. In order to enable the frame of the machine to absorb this high pressure the frame must be made of heavy sectional irons resulting in a heavy frame of great strength. This, however, increases the production costs. Another drawback to the known marking machines is that it may be difficult to adjust the penetration depth of the embossing characters into the surface of the object, the penetration depth being dependent on the hardness of the material. A third drawback is that an unevenness or a foreign body, as e.g. a mill scale, on the object will have a damaging influence on the characters embossed on the object. A foreign body under one of the outer embossing wheels may e.g. make the embossing head with the embossing wheel shaft tilt, and thereby it may cause the embossing depth of the different characters of the embossing wheels to vary, dependent on the distance between each embossing wheel and the foreign body. Consequently the embossed characters on the object will be difficult to read or may even be illegible.
The object of the invention is to provide a machine of the type as stated in the opening paragraph having a frame that is light as compared with the frame of the known machines, and that provides a predetermined penetration depth of the embossing characters into the object, as well as reduces considerably the influence of the unevennesses and the foreign bodies on the completed embossing result.